This invention relates to means for supporting an arched roof of a furnace. A rectangular electric arc furnace is typical of furnaces to which the invention applies.
Conventional non-tilting electric arc furnaces comprise an open topped metal shell which has internal walls and a bottom lined with refractory material. The roof of such furnaces is usually composed of refractory bricks formed in an arch. The ends of the arch bear against laterally adjacent skewback bricks which are supported on the top of the furnace walls. As is known, the arch tends to sag and force the skewbacks outwardly but they are restrained against sliding laterally in which case compressive forces are developed in the arch which prevent it from collapsing.
Customarily, the refractory lined furnace shell rests on a foundation which also supports rows of verticle buckstays or columns from which the roof is suspended.
A problem with this prior arrangement is that the body of the furnace expands laterally more at its bottom than at its top since the bottom region is hotter because of it being occupied by molten metal. There is also hydrostatic stress developed by the molten metal which tends to bulge the furnace outwardly near the bottom. The lateral forces of expansion are transferred from the furnace shell to the buckstays which tend to rotate, thus causing high stress to be developed between the skewbacks and the arched roof. It is well known that this may damage the roof and skewbacks.